Fertilisation

Question 1

What are the two reactions that occur during the fertilisation process?

Answer 1

1. Acrosome reaction

2. Cortical reaction

Question 2

What is the acrosome reaction?

Answer 2

Digestive (hydrolytic) enzymes, released from the sperm’s acrosome, digest the zona pellucida, allowing the sperm to move to the cell membrane of the egg.

Question 3

What is the cortical reaction?

Answer 3

Cortical granules are released from the egg cell’s vesicles into the space between the cell membrane and the zona pellucida. The chemicals from the cortical granules cause the zona pellucida to thicken, making it impenetrable to other sperm, ensuring only one sperm fertilises the egg.

Question 4

Describe the process of fertilisation.

Answer 4

1. Sperm swim towards egg in oviduct
2. One sperm makes contact with the zona pellucida- acrosome reaction occurs
3. Sperm head fuses with cell membrane of egg- cortical reaction occurs
4. Sperm head (tail is discarded) enters egg cell
5. Sperm nucleus fuses with nucleus of egg cell